Several thousand Southwest passengers who tried to buy discounted flights ended up with multiple bookings and multiple credit-card charges.

An effort by Southwest Airlines to celebrate reaching 3 million Facebook friends turned into a public-relations mess when several thousand passengers who tried to buy discounted flights Friday ended up with multiple bookings and multiple credit-card charges because of a computer glitch.

To celebrate the Facebook milestone, Southwest offered as much as 50% off on flights, with several restrictions. But the airline's online system malfunctioned because of an unusually high number of bookings from passengers hoping to take advantage of the deals Friday.

On Sunday, the Dallas airline issued a statement saying it had resolved all the problems by deploying extra staff to cancel the erroneous bookings and refunding the extra charges.

"By initiating an 'all-hands-on-deck' approach, we have identified all customers impacted and proactively initiated refunds back to their financial institutions for any erroneous bookings," the airline said.

Airline spokeswoman Ashley Dillon said the problem occurred when the airline's site booked duplicative flights each time a visitor to the website tried to refresh the page.

She said she didn't know exactly how many erroneous bookings were made but added "we know several thousands of people were impacted."

The airline had promised to cancel all multiple bookings and refund all duplicate charges. If an extra charge resulted in an overdraft charge, Southwest also promised to reimburse customers for that cost.

On Southwest's Facebook page, most of the hundreds of comments posted by passengers over the weekend were positive, with many saying the airline reacted quickly to the problem.

But a few were angry, including a woman from Santa Cruz who posted that she had waited on the phone for two hours to talk to an airline representative about six extra bookings that amounted to $1,900.